Some sports books didn't even wait until the clock ran out in the Ravens win over the New England Patriots to set the line. At the LVH sports book, a line favoring the 49ers by 4.5 points was put up just before the 2-minute warning, and bettors didn't waste any time to get money down on the game.

"We've got money coming in as we speak, it looks like it will be good on both sides," said LVH book director Jay Kornegay. "These teams mirror each other, but the 49ers are a bit more sexy now than the Ravens."

At William Hill, which operates 75 betting parlors in Nevada, oddsmakers opened the game with the 49ers a 5-point favorite, as did some other books. But it was quickly bet down to 4.5 points, a line that seemed to be holding in the early betting.

"We had what I consider a large bet come in at 5 points and moved down from there," said Vaccaro, who said he believes the line will hold between 4 and 4 1/2 points until close to the day of the game.

Baltimore already is the first underdog of more than a touchdown to win both the division and championship playoff rounds. The Ravens were 7.5-point underdogs to the Patriots before beating them 28-13 to win the AFC title game.

"The Ravens are the hot team now but they're not getting a lot of support from the public," Kornegay said. "These are very similar teams, both can run the ball well, play smash mouth football and have two quarterbacks playing very good football."